comparison impellerpump

[Technorunner]

How much better is the beltdriven impeller vs the drive driven impellerpump?
if i know correctly the beltdriven takes the water thru the bottom hull insted of thru the drive is that right?
Is it a bigger hose diam. to the belt driven pump?

 

[Don S]

Re: comparison impellerpump

What engine and drive are we talking about?

 

[Technorunner]

Re: comparison impellerpump

Its an Alpha one gen1. The Engine is a converted 4.3 vortech with CPI injection. Since i got a rather large heat exchanger i want as much raw water going thru it as possible. And as much raw water thru the Aluminum EM as well. So if the belt driven pump has better flow then im thinking of putting that one one the engine instead of the one mounted in the drive. il just remove the impeller and plug the pipe coming out of the drive. If the water going thru thes drive does any cooling on the drive it shouldent be any problem since im going with hullthru exhaust.

 

[Don S]

Re: comparison impellerpump

IF you run in salt water, I sure hope you have the manifolds included in the fresh water cooling, and if they are, you want the engine driven pump. Even Mercruiser recommends it.

 

[Technorunner]

Re: comparison impellerpump

they are not included on the internal cooling but im running in a freshwater lake. but they do have Zink anodes so should be fine.
But does the engine driven impeller pump take its water from thru the hull in the bottom or thru the drive ?

 

[Bondo]

Re: comparison impellerpump

they are not included on the internal cooling but im running in a freshwater lake. but they do have Zink anodes so should be fine.
But does the engine driven impeller pump take its water from thru the hull in the bottom or thru the drive ?

Ayuh,.... Either or the other, but never both....

It depends how ya plumb it...
Bravos, 'n Volvos can draw through the drive,...
Or ya could go with a sea strainer, 'n thru-hull fittin'...

 

[achris]

Re: comparison impellerpump

The simple answer to your original question is that the engine mounted (belt driven) pump will pump about twice as much water as the drive impeller.. That said, I had closed cooling (including exhaust manifolds) on my previous V6 (1994) with drive impeller and never had a problem. When I bought my new engine (2006 :facepalm, if I wanted the $4000 closed cooling system I would have been required to add the engine driven pump too....

Generally the Merc engine mounted pumps pull their water from either a transom mounted pick-up or a through hull pick-up. Either way remember to put a valve in the line, and have a BIG sign on the dash to the effect "WATER PICK-UP CLOSED". I've seen the result of too many engines started with the valve closed.... Not a pretty sight....

Chris........

 

[Technorunner]

Re: comparison impellerpump

Thanks Chris. That was the answer i was looking for .
Yup i have seen and smelled it to when they have forget to open the waterline valve.
That was not my boat but i was close enough when it happend.

So when the project was delayed one more season i can as well build in a engine driven pump.

 

[zbnutcase]

Re: comparison impellerpump

Its an Alpha one gen1. The Engine is a converted 4.3 vortech with CPI injection. Since i got a rather large heat exchanger i want as much raw water going thru it as possible. And as much raw water thru the Aluminum EM as well. So if the belt driven pump has better flow then im thinking of putting that one one the engine instead of the one mounted in the drive. il just remove the impeller and plug the pipe coming out of the drive. If the water going thru thes drive does any cooling on the drive it shouldent be any problem since im going with hullthru exhaust.

The pump in the drive cools the upper box when on plane as its up out of the water. Leave impeller, cut or remove water hose from bell to transom plate, and cap fitting on inside of boat.